Taiwania 65(2): 101‒108, 2020 DOI: 10.6165/tai.2020.65.101

Ceropegia phuchongensis (, ), a new species from eastern Thailand

Manit KIDYOO*, Kamonchanok SUWANNAKOTE

Plants of Thailand Research Unit, Department of Botany, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand. *Corresponding author’s email: [email protected]

(Manuscript received 7 November 2019; Accepted 5 February 2020; Online published 14 February 2020)

ABSTRACT: A new species from Phu Chong-Na Yoi National Park, Ubon Ratchathani Province, eastern Thailand, Ceropegia phuchongensis Kidyoo & K. Suwann. )Apocynaceae, Asclepiadoideae), is described, illustrated and compared with the related C. tenuicaulis Kidyoo. The new species differs in corolla tube shape, color and trichomes inside the corolla tube, as well as pollinium and corpusculum shape. In addition, the gynostegium surfaces of the two species also support the distinctiveness of the new species.

KEY WORDS: Apocynaceae, Asclepiadoideae, Ceropegieae, dry deciduous forest, grass-like habit, Thailand, Tiloris.

INTRODUCTION this was also spotted by a nature photographer about 500 kilometers away, at Khao Yai National Park, Ceropegia L., according to the phylogenetically- Nakhon Ratchasima Province, growing in similar based concept, is currently the most species-rich environmental conditions, The photographer, Chaiwat of the subfamily Asclepiadoideae (Apocynaceae), Tunkpradit, distributed his photographs to a facebook encompassing more than 700 species with the inclusion of group named ‘Wild of Thailand’. Examination the former species and the stapeliads (Bruyns and comparison of vegetative and reproductive et al., 2017). The circumscription of the genus is thus structures indicated that this plant did not belong to any broadened substantially, resulting in lower morphological known Ceropegia species. Thereby, it is here described conformity in the group. In the morphology-based concept, as a new species and named C. phuchongensis. Detailed Ceropegia sensu stricto (Linnaeus, 1753) is, despite comparison of morphological characteristics between huge variation, traditionally characterized by flowers the new species and its putatively most close relative is with a corolla united to form a tubular to urceolate provided. structure with a basal portion that is more or less inflated, and usually connate at tip to form a cage-like structure MATERIALS AND METHODS (Huber, 1957; Li et al., 1995; Meve, 2002). Ceropegia sensu stricto includes over 200 species Plant materials were collected in their natural and has a distribution from Southeast , China, , habitats between 2012 and 2017. Voucher specimens , tropical Arabia, the Canary Islands, , were prepared and deposited at BKF and BCU. Papua New Guinea and Northern (Huber, 1957; Morphological characters of the freshly collected Li et al., 1995; Meve, 2002; Thaithong et al., 2018). In specimens and the preserved specimens in the herbaria: Thailand, there are 18 described species (Kidyoo, 2018; BK, BKF, K, L, BM, P, QBG and BCU were examined Thaithong et al. 2018), with new species being regularly and compared. The morphological characters of discovered and further unknown actually being vegetative and reproductive parts were mostly observed under investigation. A new species to be described here under light microscope (LM). In addition, observations has been discovered in northeastern Thailand, the region of floral structures were made under scanning electron locally known as ‘Isan’ (including the northeastern and microscope (SEM). The gynostegia were cut and eastern floristic regions) which is the area with the separated from the flowers and preserved in 70% ethanol greatest diversity of Ceropegia in Thailand (Meve, 2009; for at least 24 hours before being dehydrated in alcohol Kidyoo, 2018; Thaithong et al., 2018). This unknown series and subsequently critical-point dried with liquid Ceropegia species was first found more than fifteen CO2. The dried specimens were then mounted on the years ago in Phu Chong-Na Yoi National Park, Ubon stubs and coated with gold. Lastly, the surface of Ratchathani province by Hasachai Boonnuang, who gynostegia were observed under a JSM-6610 LV drew my attention to the plant. It was found growing in microscope at 15 KV and compared with those of the sandy soil, in the open areas of dry deciduous similar C. tenuicaulis, revealed in previously published dipterocarp forest. Subsequently, in September 2014, studies.

101 Taiwania Vol. 65, No. 2

Fig 1. Reproductive structures of Ceropegia phuchongensis sp. nov.(A-C) and C. tenuicaulis (D-F): A, D. Flowers; B, E. Longitudinal sections of corolla tubes; C, F. Pollinaria. Photographs by M. Kidyoo. 102 2020 Kidyoo & Suwannakote: Ceropegia phuchongensis sp. nov. from Thailand

Fig 2. SEM photographs of gynostegium and corona of Ceropegia phuchongensis sp. nov. (A-C) and C. tenuicaulis (D-F). A, D. Top view of gynostegia; B, E. Side view of gynostegia (stipes were removed); C, F. Basal parts of staminal corona lobes. 103 Taiwania Vol. 65, No. 2

Table 1. Morphological comparison of Ceropegia phuchongensis and the similar species.

Characters C. phuchongensis C. tenuicaulis Stem 35–50 cm tall, unbranched, glabrous 30–50 cm tall, unbranched, glabrous linear to linear-lanceolate, 4.5–8.7 × 0.14–0.4 cm, glabrous linear to linear-lanceolate, 5–10.5 × 0.15–0.25 cm, glabrous Peduncle 0.8–2 cm length, glabrous 1–2.7 cm length, glabrous Pedicel 4–7 mm length, 0.5–0.8 mm in diam., glabrous 4–8 mm length, 0.8–1 mm in diam., glabrous Calyx lobes linear-lanceolate, 2.7–3.5 × 0.3–0.5 mm, glabrous lanceolate, 1.4–1.7× 0.4–0.5 mm, glabrous Corolla tube globose, 0.7–1.0 cm length, inflated at midlength, 0.6– tubular-urceolate, 1.7–2.2 cm length, slightly inflated at 0.9 cm in diam.; inside the inflated portion yellowish base, 0.5–0.6 cm in diam.; inside the inflated portion white with irregular purplish brown dots (basally) and purplish brown, concentrical with scattered, stiff, 0.8– broad stripes (apically), with whitish, wrinkled and 0.9– 1.5 mm long trichomes 1.5 mm long trichomes Corolla lobes narrowly linear, 3.9–6 × 0.15–0.2 cm, covered with narrowly linear, 2.6–3.5 × 0.08–0.17 cm, covered with purple hairs, leaving hair free orifices basally purplish white to purple hairs, leaving hair-free orifices basally Gynostegium interstaminal corona lobes with a few trichomes on the interstaminal corona lobes with a beard of trichomes inner side and margins; epidermis of the lower parts of inside; epidermis of staminal corona lobes covered with staminal corona lobes covered with conical papillae pointed (trichome-like) papillae Pollinaria pollinia teardrop-shaped, 0.49–0.52 × 0.31–0.34 mm; pollina ovoid, 0.53–0.57 × 0.41–0.42 mm; corpusculum corpusculum spathulate with rounded apex, 0.32–0.35 spathulate with rounded apex, 0.40–0.41 × 0.19–0.21 × 0.14–0.16 mm mm

RESULTS 0.7–1.0 cm length and 0.6–0.9 diam. which is inflated at its mid-length. The interior of this inflated part is yellowish Examination of the morphological characteristics of white with irregular purplish brown dots and stripes, and the new species in comparison to the similar C. densely covered with wrinkled, whitish trichomes of 0.9– tenuicaulis showed that both species are characterized 1.5 mm length. In contrast, C. tenuicaulis has an ovoid- by grass-like habit, with slender, erect and usually tubular corolla tube of 1.7–2.2 cm length and 0.5–0.6 cm unbranched stems that arise from a tuber, and bear linear diam. The tube has a slightly inflated basal portion and a leaves and 1-flowered cymes with a slender peduncle. long narrow upper part. The interior of its inflated part is Their corolla lobes are linear, covered with purple plain purplish brown and covered with scattered white trichomes on the adaxial surface and margins. In full trichomes of 0.7–1.4 mm length. bloom, the distal portions of these lobes are not twisted, Type: THAILAND. Ubon Ratchathani: Phu Chong- the basalmost parts are glabrous to leave (5) orifices. Na Yoi National Park, 450 m, 13 September 2012, M. Despite their similar corolla lobes, there is a clear Kidyoo 1570 (holotype, BKF!, isotype, BCU!). distinction between the two species in features of the Description: Herbs, perennial, erect, not twining, calyx, corolla tube, gynostegium and pollinarium (Figs with clear exudate in all vegetative parts. Rootstock 1 & 2, Table 1). Detailed comparison will be provided in tuberous; tubers subglobose to globose, smooth, light Discussion. brown, 1.6–2.2 cm in diam. Stem terete, solitary, Scanning electron micoscopic studies of gynostegium glabrous, unbranched, 35–50 cm tall, 1.1–2 mm in diam., with corona, again, show a high level of concordance green when young and turning brown with age; between the two elements. However, ultrastructural internodes 2–8 cm long. Leaves opposite, sessile; blade characters significantly support the separation in two linear to linear-lanceolate, 4.5–8.7 × 0.14–0.4 cm, different taxa. Ceropegia tenuicaulis bears interstaminal coriaceous, base attenuate, margins entire, slightly corona lobes that are densely pubescent on the inner side revolute, apex acute to acuminate; abaxial surface pale with stiff trichomes of 0.13–0.26 mm length, and staminal green, glabrous, adaxial surface green, glabrous; midrib corona lobes of which the lower portion is covered by greenish white, slightly convex on abaxial surface; pointed (trichome-like) papillae. In C. phuchongensis, lateral veins obscure on both surface. Inflorescence a 1– two clusters of a few stiff trichomes of 0.08–0.15 mm flowered cyme, extra-axillary; peduncle ascending to length covering the inner surface and scattered trichomes erect, straight, green to reddish brown, glabrous, 0.8–2 along the margins characterize its interstaminal corona cm long, 0.5– 0.7 mm in diam.; pedicel pinkish white to lobes. The surface of the lower part of its staminal corona reddish brown, 4–7 mm long, 0.5–0.8 mm in diam., lobes is covered with conical papillae (Fig. 2). glabrous; bract solitary, attached at base of pedicel, triangular-lanceolate, ca. 0.7 × 0.2 mm, green or pinkish TAXONOMIC TREATMENT white to reddish brown, apex acute. Calyx deeply 5- parted, lobes yellowish green or green, narrowly Ceropegia phuchongensis Kidyoo & K. Suwann., sp. nov. lanceolate, 2.7–3.5 × 0.3–0.5 mm, glabrous, apex Figs. 3–4 sharply acute, yellowish green with pink to reddish Diagnosis: Ceropegia phuchongensis differs from C. brown tint at apex. Corolla urceolate, upright; corolla tenuicaulis in having an ovoid to globose corolla tube of tube ovoid to globose, straight, basal part greenish white 104 2020 Kidyoo & Suwannakote: Ceropegia phuchongensis sp. nov. from Thailand

Fig 3. Illustrations of Ceropegia phuchongensis sp. nov. A. Flowering branch; B. ; C. Flower bud; D. Longitudinal section of flower showing corona and gynostegium; E. Top view of gynostegium; F. Calyx; G. Pollinarium; H. Fruit; I. Seed. Drawn by Manit Kidyoo from M. Kidyoo 1570(A-F) and M. Kidyoo 1652(G-I). 105 Taiwania Vol. 65, No. 2

Fig 4. Ceropegia phuchongensis sp. nov. A. Habitat; B. Habit; C. Flowers. All photographs by M. Kidyoo. 106 2020 Kidyoo & Suwannakote: Ceropegia phuchongensis sp. nov. from Thailand

to yellowish green and upper part reddish brown, outside C. tenuicaulis Kidyoo: THAILAND. Ubon Ratchathani: glabrous, 0.7–1.0 cm long, inflated at midlength, 0.6–0.9 Pha Taem National Park, 230 m, 13 September 2010, M. Kidyoo 1508 cm in diam.; interior of inflated part yellowish white (holotype, BCU!, isotype, BKF!). with irregular purplish brown dots and stripes, densely covered with white trichomes of 0.9–1.5 mm long; lobes DISCUSSION linear, 3.9–6 × 0.15–0.2 cm, long caudate, outside brown or purplish brown, inside reddish brown to dark brown; Ceropegia phuchongensis shows sufficient the basal portion 2.9–4 × 2.5–3 mm, loosely twisted, congruence with the morphological features with those margins reflexed, auriculate, auricles green to greenish of the section Tiloris series Attenuatae: habit primarily a brown, glabrous, the upper portion opened, margins and grass-like, stems erect, arising from globose tubers, adaxial surface densely covered with purple or purplish leaves (sub-) sessile, lanceolate to linear, inflorescences brown trichomes. Gynostegium stipitate, stipe 1–1.7 mm one- to few-flowered (Kambale and Yadav, 2019). The long, 0.8–1.2 mm in diam. Gynostegial corona double; majority of the members of the series Attenuatae occur interstaminal corona joined to form a shallow cup, 4.1– in India (Huber, 1957; Manudev et al., 2016; Kambale 4.5 mm in diam., with stiff trichomes inside, apex of and Yadav, 2019). In Thailand, prior to the discovery of lobes truncate or shallowly bifid, yellowish white; C. phuchongensis, eight species of this series have staminal corona lobes terete, 3.7–4.1 mm long, 0.25–0.3 previously been reported, including C. arnottiana Wight, mm in diam., basal part dark brown, incumbent on dorsal C. sootepensis Craib, C. thailandica Meve, C. suddeei surface of anthers, apical part usually long connivent- Kidyoo, C. acicularis Kidyoo, C. tenuicaulis Kidyoo, C. erect, yellowish white, apex acute and slightly recurved. tribounii Kidyoo and C. chuakulii Kidyoo (Meve, 2009; Pollinaria: pollinium teardrop-shaped, yellow, 0.49– Bruyns, 2017; Kidyoo, 2014a,b; Kambale and Yadav, 0.52 × 0.31–0.34 mm, translators stout, hyaline, ca. 0.09 2019; Kidyoo and Kidyoo, 2019). × 0.1 mm, corpusculum spathulate, reddish brown, 0.32– Thorough comparison of morphological characters 0.35 × 0.14–0.16 mm. Ovaries 2, ovoid, ca. 2 mm long, showed that certain species of the series are particularly 0.5 mm in diam., glabrous. Follicles usually 2 per flower, characterized by a long, slender, erect peduncle and linear-lanceolate in outline, reddish brown with age, 6.6– linear corolla lobes being tightly twisted in bud, that 8.2 cm long, 2.5–3 mm in diam. Seeds ovate-oblong, 6– make them clearly different from the other members. 8 × 1.5–1.8 mm, a silky white coma of 1.1–1.3 cm long. These species are Ceropegia thailandica, C. suddeei, C. Etymology: Ceropegia phuchongensis is named after tenuicaulis and C. phuchongensis. Among these four the Phu Chong-Na Yoi National Park, the type locality. species, C. thailandica and C. suddeei are distinguished Distribution and habitat: Ceropegia phuchongensis from the latter two species in having stems up to 30 cm is currently known from only two localities in eastern tall, peduncles of 5–11 cm length, and corolla lobes with Thailand. This plant is a perennial herb growing in sandy glandular trichomes that are tightly twisted in full bloom soil among tall grasses in the open area of dry deciduous (Meve, 2009; Kidyoo, 2014a). Ceropegia phuchongensis dipterocarp forest, at 300–450 m a.s.l. Flowering July– and C. tenuicaulis, on the other hand, develop slender October. stems of more than 30 cm length, shorter peduncles of Conservation status: Ceropegia phuchongensis is less than 3 cm length, and corolla lobes covered with endemic to Thailand, apparently rare and only known non-glandular trichomes and being opened and loosely from two localities, i.e. Phu Chong-Na Yoi National twisted only at their basal part in full bloom. Park, Ubon Ratchathani Province, where it was first Furthermore, C. phuchongensis is clearly discovered and Khao Yai National Park, Prachinburi differentiated by its linear-lanceolate calyx lobes that are Province. In Phu Chong-Na Yoi National Park, two twice as long as those of C. tenuicaulis. In addition, the populations were found at a distance of about 5 km from corolla tube of the former is swollen near its midlength each other. In each population, there were 30–40 and twice shorter than that of the latter which is slightly individuals occurring in a grass field of about 500 m2. inflated at base with a long narrow upper portion. In C. Plants usually grow in shallow soils over rock slabs. phuchongensis, the inner surface of the inflated portion These habitats are highly affected by soil erosion and is yellowish white with irregular purplish brown dots and human activities and drastically degraded. Over a 7-year densely covered with wrinkled white trichomes, whereas period, the number of plants has been rapidly reduced to in C. tenuicaulis, it is purplish brown and with scattered about 5 and 20 individuals in each of the two populations. straight trichomes arranged in 2–3 rings (Fig 1). The Following the IUCN Red List Categories and Criteria interstaminal corona lobes of the new species are (2017), C. phuchongensis should be considered as covered with a few trichomes on the inner side and critically endangered species (CR). margins, those of C. tenuicaulis, in turn, are densely bearded inside. The staminal corona lobes are Additional specimen examined (paratype): THAILAND. Ubon Ratchathani: Phu Chong-Na Yoi National Park, ornamented either with conical papillae in C. 300 m, 13 September 2012, M. Kidyoo 1571 (BCU!); 450 m, 4 phuchongensis, or pointed (trichome-like-) papillae in C. November 2017, M. Kidyoo 1652 (BCU!). 107 Taiwania Vol. 65, No. 2

tenuicaulis. Furthermore, the two species clearly differ Kambale, S.S. and S.R. Yadav. 2019. Taxonomic revision of from each other in shapes of pollinium. That of the new Ceropegia (Apocynaceae: Ceropegieae) in India. Rheedea species has a teardrop-shape, while that of C. tenuicaulis 29(1): 1–115. Kidyoo, M. 2014a. Ceropegia suddeei sp. nov. (Apocynaceae, is ovoid (Figs 1–2, Table 1). Asclepiadoideae) from northeastern Thailand. Nord. J. Bot. 32(5): 569–574. ACKNOWLEDGMENTS Kidyoo, M. 2014b. Two new species of Ceropegia (Apocynaceae, Asclepiadoideae) from eastern Thailand. We would like to express our gratitude to Associate Phytotaxa 162(2): 91–98. Professor Dr. Obchant Thaithong for her valuable comments and Kidyoo, M. 2018. A new species of Ceropegia suggestions on this manuscript. We thank Mr. Hasachai (Asclepiadoideae, Apocynaceae) from eastern Thailand. Boonnuang and Mr. Chaiwat Tunkpradit for sharing useful Phytotaxa 385(1): 031–036. information about the plant. We are grateful to the curators and Kidyoo, M and A. Kidyoo. 2019. Ceropegia chuakulii sp. nov. staff of the herbaria BKF, BK, QBG, BM, K, L, and P for the (Asclepiadoideae, Apocynaceae) from eastern Thailand. kind permission to study herbarium specimens. This research is Phytotaxa 425(5): 269–278. supported by the Rachadaphiseksomphot Endowment Fund Li, P.T., M.G. Gilbert and W.D. Stevens. 1995. 2015 of Chulalongkorn University (CU-58-066-CC). Asclepiadaceae. In: Wu ZY, Raven PH (Eds) Flora of China, Vol. 63. Science Press, Beijing & Missouri Botanical Garden, St. Louis 16: 189–270. LITERATURE CITED Linnaeus, C. 1753. Species Plantarum 1. Laurentii Salvii, Stockholm, 560 pp. Bruyns, P.V., C. Klak and P. Hanáček. 2017. A revised, Manudev, K.M., S.S. Kambale, C. Pramod and P.S. phylogenetically-based concept of Ceropegia Prakash. 2016. A new species of Ceropegia (Apocynaceae: (Apocynaceae). S. African J. Bot. 112: 399–436. Ceropegieae) from a midland lateritic hill of Kerala, India. Huber, H. 1957. Revision der Gattung Ceropegia. Memórias J. Adv. Res. 4(5): 1408–1414. da Sociedade Broteriana 12: 1–203. Meve, U. 2009. Ceropegia thailandica (Asclepiadoideae- IUCN. 2017. Standards and Petitions Subcommittee. Ceropegieae), a spectacular new Thai species. Bradleya 27: Guidelines for Using the IUCN Red List Categories and 161–164. Criteria. Version 13. Prepared by the Standards and Thaithong, O., A. Kidyoo and M. Kidyoo. 2018. Handbook Petitions Sub-Committee. of Asclepiads of Thailand. Amarin Printing and Publishing http://www.iucnredlist.org/documents/RedListGuidelines.p Public Company Limited, Bangkok, 326 pp. df [accessed 25.02.2018].

108